Support structure for mems device with particle filter

ABSTRACT

Various embodiments of the present disclosure are directed towards a microphone including a support structure layer disposed between a particle filter and a microelectromechanical systems (MEMS) structure. A carrier substrate is disposed below the particle filter and has opposing sidewalls that define a carrier substrate opening. The MEMS structure overlies the carrier substrate and includes a diaphragm having opposing sidewalls that define a diaphragm opening overlying the carrier substrate opening. The particle filter is disposed between the carrier substrate and the MEMS structure. A plurality of filter openings extend through the particle filter. The support structure layer includes a support structure having one or more segments spaced laterally between the opposing sidewalls of the carrier substrate. The one or more segments of the support structure are spaced laterally between the plurality of filter openings.

BACKGROUND

Microelectromechanical system (MEMS) devices, such as accelerometers,pressure sensors, and microphones, have found widespread use in manymodern day electronic devices. For example, MEMS accelerometers andmicrophones are commonly found in automobiles (e.g., in airbagdeployment systems), tablet computers, or in smart phones. MEMS devicesmay have a movable part, which is used to detect a motion, and convertthe motion to an electrical signal. For example, a MEMS accelerometerincludes a movable part that transfers accelerating movement to anelectrical signal. A microphone includes a movable membrane thattransfers sound to an electrical signal.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a cross-sectional view of some embodiments of amicroelectromechanical systems (MEMS) microphone having a particlefilter and a support structure.

FIGS. 2A-D illustrate top views of some alternative embodiments of theMEMS microphone of FIG. 1.

FIGS. 3A-B illustrate cross-sectional views of some embodiments of aMEMS microphone with a particle filter and a support structure.

FIG. 4 illustrates a cross-sectional view of some embodiments of anintegrated chip including some embodiments of the MEMS microphone ofFIG. 1 wire bonded to a complementary metal-oxide-semiconductor (CMOS)integrated circuit (IC) die.

FIGS. 5-13 illustrate cross-sectional views of some embodiments of amethod of forming a MEMS microphone with a particle filter and a supportstructure.

FIG. 14 illustrates a methodology in flowchart format that illustratessome embodiments of a method of forming a MEMS microphone with aparticle filter and a support structure.

DETAILED DESCRIPTION

The present disclosure provides many different embodiments, or examples,for implementing different features of this disclosure. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Moreover, “first”, “second”, “third”, etc. may be used herein for easeof description to distinguish between different elements of a figure ora series of figures. “first”, “second”, “third”, etc. are not intendedto be descriptive of the corresponding element. Therefore, “a firstdielectric layer” described in connection with a first figure may notnecessarily corresponding to a “first dielectric layer” described inconnection with another figure.

Microelectromechanical system (MEMS) devices used for acousticalapplications (e.g., MEMs microphones) are often housed within a packagestructure that has an opening (i.e., an inlet). The package structure isconfigured to provide protection of a MEMS device while the openingallows for sound waves to reach a cavity of the package structureholding the MEMS device. Within such a package structure, a MEMS devicemay be electrically coupled to an application-specific integratedcircuit (ASIC) disposed within the cavity. The MEMS device has movableparts directly overlying the opening of the package structure, and aparticle filter disposed between the movable parts and the opening ofthe package structure. The particle filter is configured to preventparticles from entering the opening of the package structure, therebymitigating particles that reach the movable parts. Particles interactingwith the movable parts may decreases performance of the MEMS device, forexample, by causing short circuits and/or decreasing an acousticoverload point (AOP) of the MEMS device.

One approach to fabricate a particle filter for a MEMS device is to formthe particle filter separate from fabricating the MEMS device and theASIC. For example, the MEMS device may be fabricated with movableelements, and the ASIC may be fabricated with semiconductor devices(e.g., transistors). A package substrate may be provided to integratethe MEMS device and ASIC. A package structure opening may be formed inthe package substrate, and subsequently, a particle filter may be formedover the package structure opening. After forming the particle filter,the MEMS device is directly attached to the particle filter. Thus, themovable elements of the MEMS device directly overlie the packagestructure opening.

A problem with the aforementioned approach is that the extra processingsteps utilized to form the particle filter and directly attach theparticle filter to the MEMS device increase time and costs associatedwith integrating the MEMS device and the ASIC on the package structure.Further, during the direct attachment process, a small thickness (e.g.,less than 0.5 micrometers) of the particle filter may result in damageand/or destruction of the particle filter, thereby reducing an abilityof the particle filter to protect the movable elements from particles.

Alternatively, the particle filter and MEMS device may be formed as anintegrated structure that can be attached to the package structure.While this approach may reduce the extra processing steps used to attachthe particle filter to the MEMS device, the small thickness (e.g., lessthan 0.5 micrometers) of the particle filter may still lead to damageand/or destruction of the particle filter.

The present disclosure, in some embodiments, relates to a method thatsimplifies the fabrication of a MEMS device with a particle filter. Themethod forms the particle filter and MEMS device as an integratedstructure prior to attaching the particle filter and MEMS device to apackage structure. Further, the method employs a support structure,which is disposed between the particle filter and the movable elementsof the MEMS device. The support structure increases a structuralintegrity of the particle filter during and/or after fabrication of theMEMS device with the particle filter, thereby reducing damage to theparticle filter. For example, while bonding the MEMS device to a supportstructure layer, the particle filter is susceptible to damage. However,the support structure eliminates or mitigates damage to the particlefilter. This increases an ability for the particle filter to blockand/or mitigate particles from interacting with the movable elements,thereby increasing a performance, reliability, and endurance of the MEMSdevice.

FIG. 1 illustrates a cross-sectional view of some embodiments of amicroelectromechanical system (MEMS) microphone 100 with a particlefilter 106 and a support structure 105.

The MEMS microphone 100 includes a MEMS structure 102, a supportstructure layer 111, a filter stack 104, and a carrier substrate 103.The filter stack 104 is disposed between the carrier substrate 103 andthe support structure layer 111. The MEMS structure 102 includesconductive wires 124 and conductive vias 122 disposed within aninter-level dielectric (ILD) structure 120 overlying the supportstructure layer 111. The MEMS structure 102 further includes a firstback plate 108, a second back plate 112, and a diaphragm 110 disposedbetween the first and second back plates 108, 112. The diaphragm 110 isspaced apart from the first back plate 108 and the second back plate 112by one or more non-zero distances. Further, the diaphragm 110 and thefirst and second back plates 108, 112 can be electrically conductive,which forms a capacitive element. In some embodiments, an electricalcontact 118 is electrically coupled to the diaphragm 110 and forms afirst terminal for the capacitive element, an electrical contact 114 iselectrically coupled to the first back plate 108 and forms a secondterminal for the capacitive element, and an electrical contact 116 iselectrically coupled to the second back plate 112 and forms a thirdterminal for the capacitive element. In some embodiments, the secondterminal and the third terminal are electrically coupled together. Insome embodiments, the electrical coupling is achieved through theconductive wires 124 and the conductive vias 122.

The diaphragm 110 includes one or more diaphragm openings 109 and may beanchored by the ILD structure 120 at multiple points. Anchoring thediaphragm 110 at the multiple points allows a boundary of the diaphragm110 to be fixed relative to the first and second back plates 108, 112.The diaphragm 110 is deformable by energy of sound waves to make thediaphragm 110 bend towards or away from the first back plate 108 and/orthe second back plate 112, as the sound waves exert pressure on thediaphragm 110 through a carrier substrate opening 101 in the carriersubstrate 103. The carrier substrate 103 has sidewalls defining thecarrier substrate opening 101 and the support structure layer 111 hassidewalls defining support structure openings 105os. The first andsecond back plates 108, 112 respectively comprise a plurality ofopenings by which air may pass through.

There is an air volume space 113 between the first and second backplates 108, 112. The air volume space 113 is above and below thediaphragm 110. Air can get out of or get into the air volume space 113through air passage ways formed by the plurality of openings in each ofthe first and second back plates 108, 112, and/or through the one ormore diaphragm openings 109 of the diaphragm 110. The air travels out ofor into the air volume space 113 as the diaphragm 110 bends towards oraway from the first back plate 108 and/or the second back plate 112. Thebending movement of the diaphragm 110 relative to the first back plate108 and/or the second back plate 112 by the sound waves changes thecapacitance of the capacitive element between the diaphragm 110 and thefirst and/or second back plates 108, 112. Such change of the capacitancecan be provided to external circuitry configured to measure thecapacitance by way of the electrical contacts 114, 116, 118. Themeasured capacitance can be translated into an acoustical signalcorresponding to sound waves that cause movement of the air.

The filter stack 104 includes a particle filter layer 104 b defining theparticle filter 106 disposed within a dielectric layer 104 a. In someembodiments, the particle filter layer 104 b may comprise polysilicon(e.g., intrinsic polysilicon), and the dielectric layer 104 a maycomprise an oxide (e.g., silicon oxide). The particle filter 106 is asegment of the particle filter layer 104 b between the carrier substrateopening 101 and the support structure 105. The particle filter 106 has aplurality of filter openings 107 configured to pass air from the carriersubstrate opening 101 to the air volume space 113. As the air travelsthrough the carrier substrate opening 101 in the carrier substrate 103to the air volume space 113, it passes through the particle filter 106,which is configured to block and/or remove particles from the air thatmay adversely affect the movement of the diaphragm 110. In someembodiments, the particles may, for example, be by-products from and/orchemicals used in a laser dicing process implemented to form the MEMSmicrophone 100, such as polysilicon, silicon dioxide, etc. The particlesinteracting with the diaphragm 110 may decrease a performance of theMEMS microphone 100 by, for example, causing short circuits (e.g.,between the first and second back plates 108, 112 and/ the diaphragm110) and/or decreasing an acoustic overload point (AOP) of the MEMSmicrophone 100.

The support structure 105 is a segment of the support structure layer111, wherein the support structure 105 comprises a same material as thesupport structure layer 111. In some embodiments, an upper surface ofthe support structure 105 and a lower surface of the MEMS structure 102are respectively disposed along a substantially straight horizontal line140. In some embodiments, the support structure layer 111 comprisessilicon, polysilicon (e.g., intrinsic polysilicon), or the like. Thesupport structure 105 comprises one or more segments (e.g., firstelongated segments 105 a of FIG. 2A) spaced laterally between the filteropenings 107 and vertically between the particle filter 106 and the MEMSstructure 102. By disposing the support structure 105 between theparticle filter 106 and the MEMS structure 102, a structural integrityof the particle filter 106 is increased. For example, during afabrication of the MEMS microphone 100, the support structure 105 may beformed over the filter stack 104. Subsequently, the MEMS structure 102is bonded to the carrier substrate 103 by way of the support structurelayer 111. The support structure 105 prevents damage and/or destructionto the particle filter layer 104 b during the aforementioned bondingprocess. Further, the support structure 105 remains in place duringsubsequent processing steps and/or during operation of the MEMSmicrophone 100. Therefore, the support structure 105 may reduce oreliminate strain and/or damage to the particle filter 106, therebyincreasing an endurance, reliability, and performance of the MEMSmicrophone 100.

FIG. 2A illustrates a top view 200 a of some alternative embodiments ofthe support structure 105 and the particle filter 106 taken along cutline A-A′ of FIG. 1. FIG. 1 illustrates some embodiments of across-sectional view taken along cut line B-B′ of FIG. 2A.

The plurality of filter openings 107 underlie the support structure 105and respectively have a circular and/or elliptical shape. The pluralityof filter openings 107 may be arranged as an array comprising columnsand/or rows across the carrier substrate opening (101 of FIG. 1). Theparticle filter 106 is configured to block and/or remove particles(e.g., by a shape/size of the filter openings 107 and/or a material ofthe particle filter layer 104 b) from air that passes from a firstsurface of the particle filter 106 to an opposite second surface of theparticle filter 106. The support structure 105 is a segment of thesupport structure layer 111 that extends over the filter openings 107and provides structural support to the particle filter 106. The supportstructure 105 includes first elongated segments 105 a that continuouslyextend between first opposing inner sidewalls 111 ia, 111 ib of thesupport structure layer 111. In some embodiments, the first elongatedsegments 105 a of the support structure 105 are laterally offset thefilter openings 107 by non-zero distances. In such embodiments, bylaterally displacing the elongated segments from the filter openings 107air may more easily flow from the filter openings 107, through thesupport structure openings 105 os, to the air volume space 113. Infurther embodiments, the support structure 105 may include any number offirst elongated segments 105 a. For example, a first elongated segment105 a may be disposed between each adjacent column of the filteropenings 107 (not shown).

In some embodiments, the filter openings 107 each have a diameter d thatmay, for example, be within a range of about 3 to 10 micrometers. Insome embodiments, if the diameter d is less than about 3 micrometers,then an ability to pass air from the first surface of the particlefilter 106 to the opposite second surface of that particle filter 106may be mitigated, thereby decreasing a performance of the MEMS devicestructure 102. In further embodiments, if the diameter d is greater thanabout 10 micrometers, then an ability of the particle filter 106 toblock and/or remove particles from the air that passes through theparticle filter 106 may be reduced. For example, the particle filteropenings 107 may be larger than the particles, such that the particlesmay pass through the particle filter openings and adversely affect themovement of the diaphragm (110 of FIG. 1).

FIG. 2B illustrates a top view 200 b of some alternative embodiments ofthe support structure 105 taken along cut line A-A′ of FIG. 1. FIG. 1illustrates some embodiments of a cross-sectional view taken along cutline B-B′ of FIG. 2B.

The support structure 105 includes first elongated segments 105 a andsecond elongated segments 105 b. The first elongated segments 105 arespectively continuously extend between first opposing inner sidewalls111 ia, 111 ib, and the second elongated segments 105 b respectivelycontinuously extend between second opposing inner sidewalls 111 ic, 111id. The first opposing inner sidewalls 111 ia, 111 ib continuouslyextend between the second opposing inner sidewalls 111 ic, 111 id.Further, the first elongated segments 105 a respectively extend in afirst direction and the second elongated segments 105 b respectivelyextend in a second direction that is orthogonal to the first direction.In some embodiments, the first elongated segments 105 a respectivelyintersect each second elongated segment 105 b. In further embodiments, afirst elongated segment 105 a may be disposed between each adjacentcolumn of the filter openings 107 and/or a second elongated segment 105b may be disposed between each adjacent row of the filter openings 107(not shown).

FIG. 2C illustrates a top view 200 c of some alternative embodiments ofthe support structure 105 taken along cut line A-A′ of FIG. 1. FIG. 1illustrates some embodiments of a cross-sectional view taken along cutline B-B′ of FIG. 2C.

The plurality of support structure openings 105 os extend through thesupport structure layer 111 and respectively have a circular and/orelliptical shape. The plurality of support structure openings 105 os maybe arranged as an array comprising columns and/or rows across thecarrier substrate opening (101 of FIG. 1). In some embodiments, theplurality of support structure openings 105 os are directly alignedabove the filter openings 107. In some embodiments, the supportstructure 105 is configured as a second particle filter. In suchembodiments, the support structure 105 is configured to block and/orremove particles (e.g., by a shape/size of the support structureopenings 105 os and/or a material of the support structure layer 111)from air that passes from a first surface of the support structure 105to an opposite second surface of the support structure 105. Thus, thesupport structure 105 may increase a structural integrity of theparticle filter 106 and function as a second particle filter, therebyfurther increasing a performance, reliability, and endurance of the MEMSmicrophone 100. In some embodiments, the support structure 105 has afirst material (e.g., silicon), and the particle filter (106 of FIG. 1)has a second material (e.g., silicon nitride, and/or polysilicon)different than the first material.

FIG. 2D illustrates a top view 200 d of some alternative embodiments ofthe particle filter 106 and the support structure 105 taken along cutline A-A′ of FIG. 1. FIG. 1 illustrates some embodiments of across-sectional view taken along cut line B-B′ of FIG. 2D.

The plurality of support structure openings 105 os extend through thesupport structure layer 111 and respectively have a polygon shape (e.g.,a triangle, a rectangle, a pentagon, etc.). The plurality of filteropenings 107 underlie the support structure 105 and respectively have acircular and/or elliptical shape. Thus, the filter openings 107 mayrespectively have a different shape than the support structure openings105 os. The plurality of support structure openings 105 os arerespectively larger than a corresponding underlying filter opening 107.In further embodiments, the support structure openings 105 os mayrespectively be smaller than a corresponding underlying filter opening107 (not shown). In further embodiments, the support structure 105functions as a second particle filter with different opening shapes thanthe particle filter 106. This may further decrease an ability forparticles to reach the MEMS structure (102 of FIG. 1), thereby furtherincreasing a performance, reliability, and endurance of the MEMSmicrophone (100 of FIG. 1).

FIG. 3A illustrates a cross-sectional view of a MEMS microphone 300 acorresponding to some alternative embodiments of the MEMS microphone 100of FIG. 1.

In some embodiments, the particle filter layer 104 b comprises a lowerparticle filter layer 302, a middle particle filter layer 304, and anupper particle filter layer 306. The lower particle filter layer 302may, for example, be or comprise silicon, a nitride, silicon nitride, orthe like and/or have a thickness within a range of about 0.2 to 1micrometer. The middle particle filter layer 304 may, for example, be orcomprise polysilicon, un-doped polysilicon, or the like and/or have athickness within a range of about 0.2 to 1 micrometer. The upperparticle filter layer 306 may, for example, be or comprise silicon, anitride, silicon nitride, or the like and/or have a thickness within arange of about 0.2 to 1 micrometer. In some embodiments, the layerswithin the particle filter layer 104 b may each have a substantiallysame thickness. In further embodiments, the lower particle filter layer302 and the upper particle filter layer 306 may comprise a same material(e.g., silicon nitride). In some embodiments, the particle filter layer104 b includes a polysilicon layer (e.g., the middle particle filterlayer 304) disposed between two silicon nitride layers (e.g., the lowerand upper particle filter layers 302, 306) and configured to decrease astress induced upon the particle filter 106, thereby increasing astructural integrity and reliability of the particle filter 106. In yetfurther embodiments, the conductive vias 122, conductive wires 124,first and second back plates 108, 112, the diaphragm 110, and theparticle filter 106 may respectively comprise a same material (e.g.,metal, polysilicon, or the like).

FIG. 3B illustrates a cross-sectional view of a MEMS microphone 300 bcorresponding to some alternative embodiments of the MEMS microphone 100of FIG. 1.

The filter stack 104 includes a first dielectric layer 104 a, a particlefilter layer 104 b, a second dielectric layer 104 c, and a thirddielectric layer 104 d. In some embodiments, the first, second, andthird dielectric layers 104 a, 104 c, 104 d may be or comprise a firstmaterial (e.g., an oxide, such as silicon dioxide) and the particlefilter layer 104 b may be or comprise a second material (e.g., a nitride(such as silicon nitride), polysilicon, etc.) different than the firstmaterial. Further, as illustrated in FIG. 3B, the support structurelayer 111 has a plurality of substrate sidewalls that define a pluralityof support structure openings 105 os and the particle filter layer 104 bhas a plurality of particle filter sidewalls that define the pluralityof filter openings 107. In some embodiments, the plurality of substratesidewalls are laterally aligned with the plurality of particle filtersidewalls. In such embodiments, the plurality of support structureopenings 105 os respectively overlie a corresponding filter opening 107and the support structure 105 is configured as a second particle filter,as illustrated and described in FIG. 2C.

FIG. 4 illustrates a cross-sectional view of some embodiments of anintegrated chip 400 including some alternative embodiments of the MEMSmicrophone 100 of FIG. 1 wire bonded to a complementarymetal-oxide-semiconductor (CMOS) integrated circuit (IC) die 402.

The integrated chip 400 includes the MEMS microphone 100 laterallyadjacent to the CMOS IC die 402 and disposed within a cavity 403 of apackage 401. In some embodiments, the support structure layer 111 of theMEMS microphone 100 includes the support structure 105 configured toincrease a structural integrity of the MEMS microphone 100. In someembodiments, the CMOS IC die 402 may be an application-specificintegrated circuit (ASIC). In some embodiments, the cavity 403 isdefined by inner sidewalls of the package 401. The package 401 includesa front-side structure 401 a and an enclosure structure 401 b. The CMOSIC die 402 and the MEMS microphone 100 are disposed on the front-sidestructure 401 a. In some embodiments, an opening (i.e., inlet) to thepackage 401 may be the carrier substrate opening 101 of the MEMSmicrophone 100, such that any air entering or leaving the cavity 403passes through the particle filter 106.

The CMOS IC die 402 includes a back-end-of-line (BEOL) metallizationstack 412 overlying a CMOS substrate 410. The BEOL metallization stackcomprises an inter-level dielectric (ILD) structure 413, interconnectwires 416, and interconnect vias 414. The CMOS substrate 410 and the ILDstructure 413 include electronic components such as transistors 408,and/or other electric components (not shown), such as one or morecapacitors, resistors, inductors, and/or diodes. The CMOS substrate 410may, for example, be or comprise a bulk semiconductor substrate or asilicon-on-insulator (SOI) substrate. The ILD structure 413 may compriseone or more stacked ILD layers, which respectively comprise a low-kdielectric (i.e., a dielectric material with a dielectric constant lessthan about 3.9), and oxide (e.g., silicon dioxide), or the like. Theinterconnect vias and wires 414, 416 may, for example, respectively beor comprise a conductive material, such as aluminum, copper, tungsten,or the like.

A solder ball 404 is disposed over each electrical contact 114, 116, 118of the MEMS microphone 100. The solder balls 404 provide contact pointsfor a plurality of bond wires 406. A bond pad 418 overlies a top layerof interconnect wires 416 and provides a wire bonding location for thebond wires 406 on the CMOS IC die 402. In some embodiments, thetransistors 408 are electrically coupled to the electrical contacts 114,116, 118 by way of the BEOL metallization stack 412, the bond wires 406,and the bond pads 418. The transistors 408 may be configured to receivesignals from the first back plate 108, the second back plate 112, and/orthe diaphragm 110.

FIGS. 5-13 illustrate cross-sectional views 500-1300 of some embodimentsof a method of forming a MEMS microphone with a particle filter and asupport structure according to the present disclosure. Although thecross-sectional views 500-1300 shown in FIGS. 5-13 are described withreference to a method, it will be appreciated that the structures shownin FIGS. 5-13 are not limited to the method but rather may stand aloneseparate of the method. Furthermore, although FIGS. 5-13 are describedas a series of acts, it will be appreciated that these acts are notlimiting in that the order of the acts can be altered in otherembodiments, and the methods disclosed are also applicable to otherstructures. In other embodiments, some acts that are illustrated and/ordescribed may be omitted in whole or in part.

As shown in cross-sectional view 500 of FIG. 5, a MEMS structure 102 isformed over a sacrificial carrier substrate 502. In some embodiments,the sacrificial carrier substrate 502 may, for example, be a bulksubstrate (e.g., a bulk silicon substrate), a silicon-on-insulator (SOI)substrate, or another suitable substrate. The MEMS structure 102includes conductive wires 124, conductive vias 122, an inter-leveldielectric (ILD) structure 120, a first back plate 108, a second backplate 112, and a diaphragm 110 disposed between the first and secondback plates 108, 112. The ILD structure 120 may be and/or comprise oneor more dielectric layers. The one or more dielectric layers may, forexample, be or comprise an oxide, such as silicon dioxide, or anothersuitable oxide. In some embodiments, a process for forming the MEMSstructure 102 includes forming a bottommost layer of the conductivewires 124 by a single damascene process, and subsequently forming abottommost layer of the conductive vias 122 by the single damasceneprocess. Further, in some embodiments, the process includes formingremaining layers of the conductive vias and wires 122, 124 by repeatedlyperforming a dual damascene process.

Additionally, the first back plate 108, the second back plate 112, andthe diaphragm 110 may be formed during the dual damascene process or thesingle damascene process of a corresponding layer of the conductivewires 124. For example, the second back plate 112 may be formedconcurrently with the single damascene process used to form thebottommost layer of the conductive wires 124. In another example, thefirst back plate 108, the second back plate 112, and the diaphragm 110may each be formed by depositing a layer of polysilicon (e.g., bychemical vapor deposition (CVD), physical vapor deposition (PVD), oranother suitable deposition process), patterning the layer ofpolysilicon according to a masking layer (not shown), and performing aremoval process to remove the masking layer. In some embodiments, theconductive wires 124, the conductive vias 122, the first back plate 108,the second back plate 112, and the diaphragm 110 may, for example,respectively comprise polysilicon, metal, or another suitable conductivematerial.

As shown in cross-sectional view 600 of FIG. 6, a carrier substrate 103is provided. In some embodiments, the carrier substrate 103 may, forexample, be or comprise a bulk substrate (e.g., a bulk siliconsubstrate), a silicon-on-insulator (SOI) substrate, or another suitablesubstrate and/or may have an initial thickness T1 within a range ofabout 250 to 725 micrometers. A filter stack 104 is formed over thecarrier substrate. The filter stack 104 includes a first dielectriclayer 104 a, a particle filter layer 104 b, a second dielectric layer104 c, and a third dielectric layer 104 d.

In some embodiments, a process for forming the filter stack 104includes: depositing the first dielectric layer 104 a over the carriersubstrate 103 and subsequently performing a first annealing process;depositing the particle filter layer 104 b over the first dielectriclayer 104 a, performing a second annealing process, and patterning theparticle filter layer 104 b to define a particle filter 106; depositingthe second dielectric layer 104 c over the particle filter layer 104 band subsequently performing a first planarization process (e.g., achemical-mechanical planarization (CMP) process); and depositing thethird dielectric layer 104 d over the second dielectric layer 104 c andsubsequently performing a second planarization process (e.g., a CMPprocess). In some embodiments, patterning the particle filter layer 104b includes: forming a masking layer (not shown) over the particle filterlayer 104 b; exposing unmasked regions of the particle filter layer 104b to one or more etchants, thereby defining the particle filter 106; andperforming a removal process to remove the masking layer. In someembodiments, the layers of the filter stack 104 may respectively, forexample, be deposited and/or grown by CVD, PVD, atomic layer deposition(ALD), thermal oxidation, or another suitable deposition process. Infurther embodiments, the first, second, and third dielectric layers 104a, 104 c, 104 d may respectively be formed by plasma-enhanced chemicalvapor deposition (PECVD), high density plasma chemical vapor deposition(HDPCVD), low pressure chemical vapor deposition (LPCVD), or anothersuitable deposition process.

In some embodiments, the first dielectric layer 104 a may, for example,be or comprise an oxide, such as silicon dioxide, or another dielectricmaterial and/or may have a thickness within a range of about 10 to 40micrometers. In some embodiments, the particle filter layer 104 b may,for example, be or comprise polysilicon, silicon nitride, or the likeand/or may have a thickness within a range of about 0.5 to 10micrometers. In some embodiments, the second dielectric layer 104 c may,for example, be or comprise an oxide, such as silicon dioxide, oranother dielectric material and/or may have a thickness of about 2micrometers. In further embodiments, the third dielectric layer 104 dmay, for example, be or comprise an oxide, such as silicon dioxide, oranother dielectric material and/or may have a thickness of about 1micrometer. In further embodiments, the first, second, and thirddielectric layers 104 a, 104 c, 104 d may respectively be or comprise asame material.

As shown in cross-sectional view 700 of FIG. 7, a support structurelayer 111 formed on the third dielectric layer 104 d. In someembodiments, the forming process includes bonding the support structurelayer 111 to the third dielectric layer 104 d. In such embodiments, thebonding process may, for example, be a fusion bonding process, oranother suitable bonding process. In some embodiments, the supportstructure layer 111 may, for example, be a bulk substrate (e.g., a bulksilicon substrate), a silicon-on-insulator (SOI) substrate, or anothersuitable substrate with an initial thickness T2. After performing thebonding process, a thinning process is performed on the supportstructure layer 111 to reduce the initial thickness T2 of the supportstructure layer 111 to a thickness Tms. In some embodiments, thethickness Tms is within a range of about 10 to 200 micrometers. In someembodiments, the thinning process is performed by a mechanical grindingprocess, a CMP process, some other thinning process, or any combinationof the foregoing. For example, the thinning process may be performedwholly by a mechanical grinding process.

In further embodiments, the support structure layer 111 may be formed bydepositing the support structure layer 111 over the filter stack 104.The deposition process may, for example, be or comprise CVD, PVD, LPCVD,PECVD, or another deposition process. For example, the depositionprocess be performed wholly by a CVD process, such as PECVD. In suchembodiments, the support structure layer 111 may, for example, be orcomprise polysilicon, intrinsic polysilicon, or the like and/or may havea thickness of about 4 micrometers. This may reduce a physical straininduced upon the particle filter 106 (e.g., by omitting the bondingprocess and/or the thinning process of FIG. 7), and/or decrease cost andtime associated with forming the support structure layer 111.

As shown in cross-sectional view 800 of FIG. 8, the support structurelayer 111 is patterned, thereby defining support structure openings 105os extending through the support structure layer 111 and a supportstructure 105. In some embodiments, the support structure layer 111 ispatterned in such a manner that the support structure 105 is configuredas a second particle filter, such as illustrated and described in FIGS.3B and/or 2C. In some embodiments, a process for patterning the supportstructure layer 111 includes: forming a masking layer over the supportstructure layer 111; exposing unmasked regions of the support structurelayer 111 to one or more etchants (e.g., sulfur fluoride, such as sulfurhexafluoride (SF₆), etc.), thereby defining a support structure 105; andperforming a removal process to remove the masking layer. In someembodiments, the aforementioned patterning process includes performing adry etch process, a plasma etch process, or another suitable etchprocess.

As shown in cross-sectional view 900 of FIG. 9, the support structurelayer 111 is bonded to the MEMS structure 102. In some embodiments, thebonding process may, for example, be a fusion bonding process, oranother suitable bonding process. After performing the bonding process,a thinning process is performed on the carrier substrate 103 to reducethe initial thickness T1 of the carrier substrate to a thickness Tcs. Insome embodiments, the thickness Tcs is within a range of about 200 to400 micrometers. In some embodiments, the thinning process is performedby a mechanical grinding process, a CMP process, some other thinningprocess, or any combination of the foregoing. For example, the thinningprocess may be performed wholly by a mechanical grinding process.

As shown in cross-sectional view 1000 of FIG. 10, the structure of FIG.9 is flipped and a removal process is performed on the sacrificialcarrier substrate (502 of FIG. 9), thereby removing the sacrificialcarrier substrate (502 of FIG. 9). In some embodiments, the removalprocess of the sacrificial carrier substrate (502 of FIG. 9) includes:performing a grinding process (e.g., a mechanical grinding process) onthe sacrificial carrier substrate (502 of FIG. 9); and performing a wetetch process on a remaining portion of the sacrificial carrier substrate(502 of FIG. 9) and/or the ILD structure 120, thereby exposing an uppersurface of the ILD structure 120. In some embodiments, after removingthe sacrificial carrier substrate (502 of FIG. 9), a deposition processis performed to form one or more ILD layers (e.g., comprising silicondioxide) on the upper surface of the ILD structure 120. In suchembodiments, the one or more ILD layers are a part of the ILD structure120 and may be deposition by, for example, PECVD.

Also as shown in FIG. 10, electrical contacts 114, 116, 118 are formedin the ILD structure 120. In some embodiments, a process for forming theelectrical contacts 114, 116, 118 includes: forming a masking layer (notshown) over the ILD structure 120; exposing unmasked regions of the ILDstructure 120 to one or more etchants, thereby defining electricalcontact openings; and depositing the electrical contacts 114, 116, 118in the electrical contact openings. In such embodiments, the electricalcontacts 114, 116, 118 may, for example, be deposited and/or grown byelectroless plating, sputtering, electroplating, or another suitabledeposition process. In some embodiments, the electrical contacts 114,116, 118 may respectively, for example, be or comprise gold, nickel, orthe like.

As shown in cross-sectional view 1100 of FIG. 11, an upper masking layer1102 is formed over the upper surface of the ILD structure 120. Theupper masking layer 1102 covers the electrical contacts 114, 116, 118and is configured to protect the electrical contacts 114, 116, 118during subsequent processing steps. A lower masking layer 1104 is formedon a lower surface of the carrier substrate 103. After forming the lowermasking layer 1104, the carrier substrate 103 is patterned according tothe lower masking layer 1104, thereby forming the carrier substrateopening 101 in the carrier substrate 103. In some embodiments,patterning the carrier substrate 103 includes performing a dry etchprocess, such as a plasma etch process and/or a deep reactive-ion etch(DRIE) process.

As shown in cross-sectional view 1200 of FIG. 12, a patterning processis performed on the structure of FIG. 11 according to the upper and/orlower masking layers 1102, 1104, thereby defining a MEMS microphone 100.In some embodiments, the patterning process on the structure of FIG. 11includes performing a wet etch process and/or exposing the structure ofFIG. 11 to one or more etchants. The patterning process removes aportion of the ILD structure 120, thereby defining the air volume space113. Further, the patterning process removes the first, second, andthird dielectric layers 104 a, 104 c, 104 d from above and below theparticle filter 106. After performing the patterning process, a removalprocess is performed to remove the upper and lower masking layers (1102,1104 of FIG. 11). During the etching process, the particle filter 106 isfreed and may be moved by the etchant and/or by movement of the MEMSmicrophone. The support structure 105 limits movement of the particlefilter 106 so as to prevent damage to the particle filter 106 (e.g., soas to prevent the particle filter 106 from contacting the first backplate 108).

As shown in cross-sectional view 1300 of FIG. 13, the MEMS microphone100 is bonded to a front-side structure 401 a of a package 401. In someembodiments, the bonding process may, for example, be a fusion bondingprocess, or another suitable bonding process. The support structure addsstructural support and/or limits movement of the particle filter 106 soas to prevent damage to the particle filter 106 during theaforementioned bonding process. Further, after performing the bondingprocess, the electrical contacts 114, 116, 118 are wire bonded to theCMOS IC die 402. Furthermore, after the wire bonding process, anenclosure structure 401 b is formed over the front-side structure 401 a,thereby defining a cavity 403. In some embodiments, an opening (i.e.,inlet) to the package 401 may be the carrier substrate opening 101 ofthe MEMS microphone 100, such that any air entering or leaving thecavity 403 passes through the particle filter 106.

In some embodiments, because the first and second dielectric layers 104a, 104 c surround the particle filter layer 104 b during the processingsteps of FIGS. 6-12, the particle filter layer 104 b is protected fromparticles and/or damage due to the processing steps of FIGS. 6-12. Thus,particles may not accumulate around and/or on the particle filter layer104 b during the processing steps of FIGS. 6-12, thereby increasing anability of the particle filter 106 to block particles from reaching thediaphragm 110. In further embodiments, because the particle filter 106is freed by the wet etch process of FIG. 12, damage to the particlefilter 106 may be mitigated. For example, in yet further embodiments, ifthe particle filter 106 was freed by a dry etch process, the particlefilter 106 may be more prone to collecting particles and/or havingstructural damage, thereby decreasing a performance of the particlefilter 106.

FIG. 14 illustrates a method 1400 of forming a MEMS microphone with aparticle filter and a support structure in accordance with someembodiments. Although the method 1400 is illustrated and/or described asa series of acts or events, it will be appreciated that the method isnot limited to the illustrated ordering or acts. Thus, in someembodiments, the acts may be carried out in different orders thanillustrated, and/or may be carried out concurrently. Further, in someembodiments, the illustrated acts or events may be subdivided intomultiple acts or events, which may be carried out at separate times orconcurrently with other acts or sub-acts. In some embodiments, someillustrated acts or events may be omitted, and other un-illustrated actsor events may be included.

At act 1402, a MEMS structure is formed over a sacrificial carriersubstrate. The MEMS structure includes a first back plate, a second backplate, and a diaphragm disposed between the first and second backplates. FIG. 5 illustrates a cross-sectional view 500 corresponding tosome embodiments of act 1402.

At act 1404, a carrier substrate is provided and a filter stack isformed over the carrier substrate. The filter stack includes one or moredielectric layers and a particle filter layer having a particle filterdisposed in the one or more dielectric layers. FIG. 6 illustrates across-sectional view 600 corresponding to some embodiments of act 1404.

At act 1406, a support structure layer is formed over the filter stack.FIG. 7 illustrates a cross-sectional view 700 corresponding to someembodiments of act 1406.

At act 1408, the support structure layer is patterned, thereby defininga support structure in the support structure layer. FIG. 8 illustrates across-sectional view 800 corresponding to some embodiments of act 1408.

At act 1410, the support structure layer is bonded to the MEMSstructure. The support structure is disposed between the diaphragm andthe particle filter. FIG. 9 illustrates a cross-sectional view 900corresponding to some embodiments of act 1410.

At act 1412, a removal process is performed to remove the sacrificialcarrier substrate. FIG. 10 illustrates a cross-sectional view 1000corresponding to some embodiments of act 1412.

At act 1414, the carrier substrate is patterned to define a carriersubstrate opening (e.g., an inlet) below the particle filter. FIG. 11illustrates a cross-sectional view 1100 corresponding to someembodiments of act 1414.

At act 1416, an etching process is performed on the MEMS structure andthe filter stack, thereby defining an air volume space around the firstback plate, the second back plate, and the diaphragm. The etchingprocess removes the one or more dielectric layers from the particlefilter. FIG. 12 illustrates a cross-sectional view 1200 corresponding tosome embodiments of act 1416.

At act 1418, the carrier substrate is bonded to a front-side structureof a package. FIG. 13 illustrates a cross-sectional view 1300corresponding to some embodiments of act 1418.

Accordingly, in some embodiments, the present disclosure relates to aMEMS microphone including a support structure disposed between aparticle filter and a diaphragm.

In some embodiments, the present application provides a microphoneincluding a carrier substrate having opposing sidewalls that define acarrier substrate opening; a microelectromechanical systems (MEMS)structure overlying the carrier substrate, wherein the MEMS structureincludes a diaphragm having opposing sidewalls that define a diaphragmopening overlying the carrier substrate opening; a particle filterdisposed between the carrier substrate and the MEMS structure, wherein aplurality of filter openings extend through the particle filter; and asupport structure layer disposed between the particle filter and theMEMS structure, wherein the support structure layer includes a supportstructure having one or more segments spaced laterally between theopposing sidewalls of the carrier substrate, wherein the one or moresegments of the support structure are spaced laterally between theplurality of filter openings.

In some embodiments, the present application provides amicroelectromechanical system (MEMS) device including a MEMS structuredisposed along an upper surface of a support structure layer, whereinthe MEMS structure includes a first back plate and a diaphragmvertically separated from the first back plate; a carrier substrateunderlying the support structure layer, wherein the carrier substratehas opposing sidewalls defining a carrier substrate opening, wherein thecarrier substrate opening underlies the diaphragm; a filter stackdisposed between the carrier substrate and the support structure layer,wherein the filter stack includes a particle filter layer having aparticle filter, wherein the particle filter includes a plurality offilter openings that extends through the particle filter layer and islaterally between the opposing sidewalls of the carrier substrate; and asupport structure disposed between the filter stack and the MEMSstructure, wherein the support structure is a segment of the supportstructure layer laterally between support structure openings that extendthrough the support structure layer.

In some embodiments, the present application provides a method formanufacturing a microelectromechanical systems (MEMS) device, the methodincludes forming a MEMS structure over a sacrificial substrate, the MEMSstructure includes a movable diaphragm; forming a filter stack over acarrier substrate, wherein the filter stack includes one or moredielectric layers and a particle filter layer having a particle filterdisposed in the one or more dielectric layers; forming a supportstructure layer over the filter stack; patterning the support structurelayer to define a support structure in the support structure layer,wherein the support structure has one or more segments; bonding thesupport structure layer to the MEMS structure; and patterning thecarrier substrate to define a carrier substrate opening, wherein the oneor more segments of the support structure are spaced laterally betweenopposing sidewalls of the carrier substrate that define the carriersubstrate opening.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. A microphone comprising: a carrier substrate having opposingsidewalls that define a carrier substrate opening; amicroelectromechanical systems (MEMS) structure overlying the carriersubstrate, wherein the MEMS structure includes a diaphragm havingopposing sidewalls that define a diaphragm opening overlying the carriersubstrate opening; a filter stack disposed between the carrier substrateand the MEMS structure, wherein the filter stack includes a particlefilter layer having a particle filter, wherein a plurality of filteropenings extend through the particle filter; and a support structurelayer disposed between the particle filter and the MEMS structure,wherein the support structure layer comprises a support structure havingfirst elongated support segments extending between a first pair ofopposing inner sidewalls of the support structure layer, wherein thefirst elongated support segments are spaced laterally between theopposing sidewalls of the carrier substrate, and wherein the firstelongated support segments respectively comprise opposing straightsidewalls that continuously extend between the first pair of opposinginner sidewalls of the support structure layer.
 2. The microphone ofclaim 1, wherein the particle filter comprises polysilicon and thesupport structure comprises silicon.
 3. The microphone of claim 1,wherein the diaphragm, the particle filter, and the support structurerespectively comprise polysilicon.
 4. The microphone of claim 1, whereinthe filter stack includes a dielectric layer disposed along an uppersurface and a lower surface of the particle filter layer, and whereininner sidewalls of the dielectric layer are aligned with the opposingsidewalls of the carrier substrate. 5-7. (canceled)
 8. The microphone ofclaim 1, wherein the support structure is disposed between the firstpair of opposing inner sidewalls and a second pair of opposing innersidewalls of the support structure layer, and wherein the second pair ofopposing inner sidewalls of the support structure layer are aligned withthe opposing sidewalls of the carrier substrate that define the carriersubstrate opening.
 9. The microphone of claim 8, wherein the supportstructure further comprises second elongated support segments, whereinthe second elongated support segments extend continuously between thesecond pair of opposing inner sidewalls of the support structure layer.10. A microelectromechanical system (MEMS) device, comprising: a MEMSstructure disposed along an upper surface of a support structure layer,wherein the MEMS structure includes a first back plate and a diaphragmvertically separated from the first back plate; a carrier substrateunderlying the support structure layer, wherein the carrier substratehas opposing sidewalls defining a carrier substrate opening, wherein thecarrier substrate opening underlies the diaphragm; a filter stackdisposed between the carrier substrate and the support structure layer,wherein the filter stack includes a particle filter layer having aparticle filter, wherein the particle filter comprises a plurality offilter openings that extends through the particle filter layer and islaterally between the opposing sidewalls of the carrier substrate; andwherein the support structure layer comprises a support structure havingone or more segments of the support structure layer, wherein the one ormore segments of the support structure have a plurality of opposingsidewalls that define a plurality of support structure openingsextending through the support structure layer, wherein when viewed fromabove the support structure openings respectively have a different shapethan the filter openings.
 11. The MEMS device of claim 10, wherein theparticle filter comprises a lower particle filter layer, an upperparticle filter layer, and a middle particle filter layer disposedbetween the upper and lower particle filter layers, wherein the upperand lower particle filter layers comprise silicon nitride, and whereinthe middle particle filter layer and the support structure comprisepolysilicon.
 12. The MEMS device of claim 10, wherein a thickness of thesupport structure is greater than a thickness of the particle filter.13. The MEMS device of claim 10, wherein a thickness of the carriersubstrate is greater than a thickness of the support structure. 14.(canceled)
 15. The MEMS device of claim 10, wherein the supportstructure openings have a polygon shape and the filter openings have acircular shape.
 16. The MEMS device of claim 10, wherein the filterstack comprises a dielectric layer, wherein the particle filter layer isdisposed in the dielectric layer, wherein inner sidewalls of thedielectric layer are aligned with the opposing sidewalls of the carriersubstrate, and wherein inner sidewalls of the support structure layerare aligned with the inner sidewalls of the dielectric layer.
 17. Amethod for manufacturing a microelectromechanical systems (MEMS) device,the method comprising: forming a MEMS structure over a sacrificialsubstrate, the MEMS structure includes a movable diaphragm; forming afilter stack over a carrier substrate, wherein the filter stackcomprises one or more dielectric layers and a particle filter layerhaving a particle filter disposed in the one or more dielectric layers;forming a support structure layer over the filter stack; patterning thesupport structure layer to define a support structure in the supportstructure layer, wherein the support structure has one or more segments;bonding the support structure layer to the MEMS structure; andpatterning the carrier substrate to define a carrier substrate opening,wherein the one or more segments of the support structure are spacedlaterally between opposing sidewalls of the carrier substrate thatdefine the carrier substrate opening.
 18. The method of claim 17,wherein forming the support structure layer comprises: fusion bondingthe support structure layer to the filter stack; and performing amechanical grinding process on the support structure layer to reduce athickness of the support structure layer to less than a thickness of thecarrier substrate; wherein the support structure layer comprises siliconand the particle filter comprises polysilicon.
 19. The method of claim17, wherein forming the support structure layer comprises: depositingthe support structure layer on an upper surface of the filter stack by achemical vapor deposition (CVD) deposition process; wherein the supportstructure layer and the particle filter respectively comprisepolysilicon.
 20. The method of claim 17, wherein forming the filterstack comprises: forming a first dielectric layer over the carriersubstrate; forming the particle filter layer over the first dielectriclayer; patterning the particle filter layer to define the particlefilter; forming a second dielectric layer over the particle filterlayer; and forming a third dielectric layer over the second dielectriclayer; wherein after forming the first dielectric layer and the particlefilter layer an annealing process is performed, wherein after formingthe second and third dielectric layers a planarization process isperformed, wherein the first, second, and third dielectric layersrespectively comprise and oxide, and wherein the particle filter layercomprises polysilicon.
 21. The microphone of claim 9, wherein the firstelongated support segments extend continuously in a first direction andthe second elongated support segments extend continuously in a seconddirection that is orthogonal to the first direction.
 22. The microphoneof claim 1, wherein a width of each first elongated support segment isless than a diameter of each filter opening.
 23. The microphone of claim1, wherein the particle filter layer comprises an upper particle filterlayer, a lower particle filter layer, and a middle particle filter layerdisposed between the upper and lower particle filter layers, wherein theupper and lower particle filter layers comprise a first material, andwherein the middle particle filter layer comprises a second materialdifferent from the first material.
 24. The MEMS device of claim 10,wherein each support structure opening in the plurality of supportstructure openings overlies a corresponding filter opening in theplurality of filter openings.